96 Intrepid stereo/gauge problem

I have a 96 intrepid and I think I have some wiring issues with it, I'm not sure what to check though and it's hard to explain. What's going on though is the gauges aren't working most of the time, but when they do work is when the car is off for about 8 hours, maybe longer. But when they do work, the stereo is insanely loud and turning it down doesn't work, we can mute it and turn it up, but that's it. But the gauges will cut back out and the stereo will be working properly. I bought it used two days ago and the problem started yesterday. Any one have an idea of what it could be and how to fix it?

Not sure how to edit posts, but here's an update. Pulled my deck out and the gauges stayed on, put it back in and they shut down again, so it is definitely a wiring issue. Does any one know where I can get wiring diagrams for the car?